Roast the beets. Preheat the oven to 425 degrees. Cut the greens off of the beets, leaving about 1/2-inch of the stems attached. Scrub the beets and place in a baking dish or ovenproof casserole. Add about 1/4 inch water to the dish. Cover tightly with a lid or foil, and bake 35 to 40 minutes, until the beets are tender. Remove from the heat and allow to cool. If not using right away, refrigerate in a covered bowl.

Line another roasting pan with foil or parchment and brush with olive oil. Peel the squash and cut in 1/2-inch thick slices. Toss with 2 teaspoons of the olive oil and salt to taste and place on the baking sheet. Roast for 20 to 30 minutes, turning halfway through, until lightly browned and tender. You can do this at the same time that you roast the beets, but watch carefully if you need to put the baking sheet on a lower shelf. Remove from the heat and allow to cool.

Meanwhile, bring a large pot of water to a boil while you stem and wash the greens. Add salt to the water, and blanch the greens for 1 minute or until tender. Transfer the greens to a bowl of cold water, then drain and squeeze out the water. Chop coarsely.

Mix together the vinegars, garlic, salt, pepper, the remaining olive oil and the walnut oil. When the beets are cool enough to handle, trim the ends off, slip off their skins, cut in half, then slice into half-moon shapes. Toss with half the salad dressing. In a separate bowl, toss the roasted squash with the remaining dressing.

Place the greens on a platter, leaving a space in the middle. Arrange the beets and squash in alternating rows in the middle of the platter. Sprinkle on the fresh herbs and the walnuts. If desired, sprinkle on crumbled feta. Serve.

Advance preparation: Roasted beets and squash will keep for 4 to 5 days in the refrigerator. Cooked beet greens will keep for about three days, and can be reheated. The salad will hold in the refrigerator for a couple of hours, but it’s prettiest when served right away.